Joining of Titanium-Matrix Composites Reinforced with SiC-CVD Fiber.

Abstract

In this study, we have been investigated on joining of titanium-matrix composites reinforced with SiC-CVD fiber (FRM) to FRM by tensile tests of the joints using butt joint, with a doubler and overlap length of 20 mm. The joinability was compared with solid state diffusion bonding and diffusion brazing using commercially pure copper and Ti-37.5Zr-15Ni-10Cu amorphous filler.As for mechanical properties of the joint, even the joint made at 1143 K for 5 min under the joining pressure of 12 MPa, which is slightly higher than that required in solid state diffusion bonding of the same material, was fractured in the base metal with tensile strength of 1400 MPa, resulting a joint efficiency of about 96%. The fiber damage decreases the strength of the joint as the joinging pressure increases. The diffusion brazability using commercially pure copper of 5 μm thickness at 1153 K was obtained good joint efficiency for 3 min under the joining pressure of 2 MPa, lower than that of diffusion bonding. In the diffusion brazability using Ti-base filler metal, the strength of the joint was equal to the strength of the base metal.Butt joint, with a doubler and overlap length of 10 and 15 mm, failed in shear at a tensile stress in the base material, resulting in a shear strength of about 125 MPa. The poor results were attributed to composites material of lower interlaminar shear strength.